Thursday, August 26, 2010

Recently, UPS showed up at my door with a large box. After a few signatures I was taking my new Microflash Pro out of the packaging to gaze upon it in reverence. Is it big? Yes. Try to imagine a front loader VCR (remember those things that played VHS tapes?) that is 2 or 3 inches shorter from left to right.

The Microflash Pro dwarfing my D300

For those of you not familiar with high speed photography you may be wondering why such a flash is needed. Speedlights are much smaller and generally more convenient, right? And if they don't provide the amount of light that is required, there are plenty of big Metz and studio strobes out there with very impressive guide numbers, right? So why a specialized flash?

The answer is the need for speed AND power. Speedlights can have very fast durations but can only do so when set on rather low light outputs. A fair work around is bringing these flashes very close to the scene. But then there's the problem of light modifiers that eat up their share of photons such as the softbox. Studio strobes put out larger quantities of light but they generally accomplish this by keeping their bulbs lit for longer periods of time, often in the order of 1/1000".

So, to have a lot of light in a very short duration requires a different beast entirely. It means dangerously high voltages and currents and large capacitors to store this energy. A new standard of safety engineering needs to be applied if such a unit is to be distributed to consumers. Is the VCR-like sizing of the Pro's flash head a necessity based on physics? Yes. Much in the same way that you need a very large gasoline engine if you require 500lb-ft of torque and 500hp. The Pro provides about the same amount of light that two Nikon SB-800s could provide at full power. But, instead of delivering that light over 1/1000 of a second, the Pro gets it done in an astonishingly fast 1/28000 of a second.

Speed and Power allow the Pro to be placed away from the subject

Even with the light modifying softbox attached, the Pro can be withdrawn comfortably away from the area in front of the lens, hence leaving plenty of space in that normally cramped area for infrared beam emitters and receivers as well as other bits of hardware typically associated with high-speed photography. I can typically operate my high speed sets at f22, iso200 and have regular Nikon speedlights take care of the secondary lighting such as backlighting and the lighting of artificial backgrounds. I get by quite well with only one Pro flash head providing the primary lighting for the scene.

The external battery has the same feel as the flash head of the Pro: think "military hardware"

As the subjects get smaller and faster, as is the case with insects in flight, the speedlights no longer provide the light that is needed to properly expose the scene without compromising iso or depth of field. In the past I have used speedlights at 1/16 power (1/10000 of a second) for many applications where this speed was sufficient. I came to realize that the speedlights were insufficient when 1/32 power (1/17000") was barely enough to freeze my insect subjects and I needed to bring the flashes within inches of the subject in order to illuminate them properly.

Zero Lag Applications?

A perhaps unforeseen benefit of the immense power of the Pro is the ability to simulate a near-zero shutter lag in the studio environment. By limiting the ambient light in the studio the high speed photographer can afford to hold the camera shutter open for a second or two in anticipation of the action without affecting the exposure. This can only be accomplished if the aperture is stopped down to f16 or f22 (already a requirement for other reasons such as DOF) and low iso sensitivities. The Pro can be triggered directly by any tripwire system such as the StopShot or the Phototrap, both of which I use extensively. Since flashes respond much faster than camera shutters (in the order of millionths of a second as opposed to the hundredths of a second required for the mechanical shutter of a DSLR to open) the photographer can come as close to the zero lag ideal as possible.

A most demanding of situations: The subject approaches the camera and is traveling over a very short distance. The infrared beam or laser beam that triggers the camera cannot be repositioned to accommodate the lag in this case because the distance traveled by the subject is too short.

How, exactly, is the above image achieved, you ask? Find out in my new book, due out later this year. Keep an eye out for a pre-orders page!